Summa Theologiae Moralis, vol. I: De Principiis

S. Th. I-II, q. 65, a. 1 ; De Virt. q. 5, a. 2.

604. Principle I. Imperfect moral virtues are not connected. — For the inchoations of moral virtues, which dispose us to choose this or that in certain circumstances, whether they are in us from nature because of a disposition of the body, or come from custom, are not connected, as experience shows : for one can be prompt to liberality who is not prompt to chastity. Those inclinations are sometimes called imperfect virtues ; but they are not true and properly so called virtues, because they do not render one perfect.

605. Principle II. Perfect moral virtues are connected, which incline us to do good steadfastly and in all circumstances, notwithstanding any difficulties. Thus according to the mind of SS. Augustine and Thomas, against Scotus. For :

a) Moral virtue, which is the habit making a good choice, cannot be without prudence, because for choosing rightly the intention of the due end, to which moral virtue disposes, is not sufficient, but good counsel, judgment, and precept about the good means to the end are also required, to which prudence disposes : for to do evil for the sake of a good end is morally evil ; whence for always acting rightly a perfect prudence is required.

b) Prudence cannot be without moral virtues ; for :

1° For the honest ordering of means, the intention of some good end is required, to which moral virtue disposes : for to order good means to an evil end is morally evil ; and the ordering of means will not be always and in all circumstances honest unless in all circumstances the intention of the due end be had, to which we are disposed only through all the perfect moral virtues.

2° Each one judges how to order according as he is affected ; therefore moral virtues are necessary that man may judge always well and in every case¹.

c) Which besides experience confirms, for a judge well disposed to justice but greedy of money, on money being offered, will judge unjustly ; and a woman chaste but timid, from fear of some evil, will consent to fornication ; and many brave, liberal, devout,... from lack of prudence choose badly the means to the end of virtue².

Hence prudence and moral virtues are mutually included, and therefore through prudence all virtues are connected. Prudence is of the essence of the definition of moral virtue, and moral virtue is of the definition of prudence insofar as this must be for a good end.

606. Observation. — The merely intellectual virtues are neither all connected among themselves nor with the moral virtues, because they are about diverse matters not ordered to one another, as is clear from the diverse sciences and arts ; all however depend on the intellect of principles, but this in turn does not depend on the others.